1. Field of the Invention
The invention relates to a signaling mechanism between different types of networks such as a Wireless Local Area Network and a Wireless Wide Area Network.
2. Description of the Related Art
Today, there exist many types of wireless networks such as Wireless Local Area Networks (WLANs) that are used to provide coverage in smaller areas such as building or plants. Other basic types of Wireless Networks include the Wireless Personal Area Network (WPAN) such as Bluetooth™ or the Wireless Wide Area Network (WWAN), which covers large geographic areas.
On one hand, WLANs are deployed by hotspot service providers in different public places such as shopping mall, hotels or airports. A WLAN allows a user of a wireless client (laptop or desktop computer equipped with PC or PCI cards) to access a plurality of services. More particularly, PC or PCI cards receive radio signals from an access point with which it is communicating and translates that signal into digital data that PCs can understand. In the WLAN, access points are provided for granting access to the user. Access points are hard-wired to a LAN. Using an ordinary RJ-45 cable, it is possible to connect an access point to a wired LAN such as an Ethernet network. Also, access points can be described as software that run on a server, however the vast majority of access points are separate pieces of hardware. Access points translate digital data from the network into radio signals that wireless clients can understand for providing services to a user, while within the coverage of the WLAN.
WLANs use unregulated frequencies. For example access points and wireless clients can communicate over channels within a 2.4 GHz frequency band. Channel 2 in the 2.4 GHz band runs specifically at 2.402 GHz. Channel 3 runs at 2.403 GHz. The 2.4 GHz frequency band has a total of 80 channels, however some countries such as the United States and Canada allow the use of different frequencies. In these mentioned countries channels 1 through 11 are used.
On the other hand, WWANs generally use digital cellular phone networks to enable wireless clients to access among other things the Internet across extensive geographic areas. Unlike WLANs, which offer limited user mobility, WWANs facilitate connectivity for mobile users, and use regulated frequencies.
In WWANs, communication occurs predominantly through the use of radio signals over different types of networks such as analog or digital cellular. As it is well known today, many wireless data communication takes place across 2G (second generation) networks such as TDMA (Time Division Multiple Access), CDMA (Code Division Multiple Access), GSM (Global System for Mobile Communication), and PDC (Pacific Digital Cellular (GSM in Japan)), or through packet-data technology over old analog systems such as CDPD (Cellular Digital Packet Data) overlay on AMPS (Advanced Mobile Telephone Service). Although traditional analog networks have been designed for voice rather than data transfer this causes some inherent problems. Some 2G and/or new 3G (third generation) digital cellular networks such as CDMA2000 or UMTS (Universal Mobile Telecommunication System) are fully integrated for data/voice transmission. Therefore, it is possible to develop 3G Wireless Wide Area Network (3G WAN).
Nowadays, 3G networks (3G WWAN) operators offer many services. However, WLAN access and 3G WWAN access are completely independent access technologies. Therefore, 3G WWANs require a complement such as a Multi-Access Environment for allowing mobile users to roam from a WLAN to a 3G WWAN and vice versa. For doing so, the Multi-Access Environment uses a technology called MobileIP for allowing roaming issues. With this complement, users may roam back and forth from a WLAN to a 3G WWAN. However, even thought the user is allowed to roam from the WLAN to the 3G WWAN, the operator is not able to manage roaming in the WLAN in view of security and billing purposes. Therefore, there is a need to improve signaling between WLANs and 3G WWANs. The invention provides a solution to this problem.